Kernel Level File Integrity Checker report #4

[Efstratios Karatzas]

During week #4:

* pefs_mount() can be supplied the "-o checksum" option, which enables
integrity checking in pefs kernel driver.
If this option is found during VFS_MOUNT(), our driver acquires a vnode for
the .pefs.checksum file and loads its header as well as the index part of
.pefs.checksum which is kept in kernel heap.
Resources are deallocated and checksum vnode vreled during pefs_unmount()
(VFS_UNMOUNT()).

* When a new pefs vnode is generated as a result of a VOP_LOOKUP() call, we
look it up in our checksum index tables. If an entry for our file is found,
we keep a pointer to that entry with the pefs vnode.
This reference will be later used e.g. during a VOP_READ() call where we
will test the checksum of the block that was retrieved from disk against
the checksum from .pefs.checksum.

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Efstratios "GPF" Karatzas